A typical gas turbine engine includes at least a compressor section, a combustion section and a turbine section. In the compressor section and in the turbine section typically lubrication fluids are necessary. Lubrication may also be necessary in other parts of the gas turbine engine or even in an aircraft which is powered by the gas turbine engine, for example in the transmission or gearbox of a helicopter. During prolonged operation metal chips may accumulate in the transmission fluid or lubrication fluid. The metal chips may be generated during normal operation (despite the presence of the lubrication fluid) as a result of grinding processes between moving parts, in particular metal parts such as transmission gears. Furthermore, a significant number of metal chips in the transmission fluid can also indicate general mechanical problems with a transmission.
Metal particles in a lubrication system are undesirable. As such, many gas turbine engines are typically equipped with a chip zapping unit (also called a “chip zapper”), which not only detects the presence of the metal particles, but also attracts them to a side surface of the lubrication system. Depending on the application, some chip zapping units also burn the metal particles to clean the lubrication fluid. For example, when a chip enters a chip detector, a capacitor is discharged through the chip to heat and burn away the unwanted particles or chips.
The chip zapper is typically immersed in the lubrication fluid together with the chip detector. The chip zapper in the magnetically attracts, for example, ferromagnetic particles suspended in the fluid. As a result, the chip detector contacts will be bridged by the particles such that the detector can issue a warning about the presence of particles in the lubrication oil systems of the aircraft or the gas turbine engine. When the warning is issued, the lubrication oil can be replaced.
The chip zapping unit (chip zapper) typically has an energy input to receive operational energy. Typically, the chip zapper in a typical control system on gas turbine engines receives electrical pulses generated by the electronic control unit (ECU) of the gas turbine engine. The electronic control unit is the central control system which receives energy from typically a permanent magnet alternator provided on a rotational shaft of the turbine or the compressor. However, in order for the chip zapper to perform its function of attracting metal particles in the lubrication fluid, the ECU must provide relatively high energy. As may be appreciated, the circuits necessary for this generally increase the footprint inside an ECU that is already challenged for space. Furthermore, such high energy power generation inside the ECU can result in additional costs to the ECU and decrease the overall reliability of the ECU. Furthermore, since the ECU has to supply pulses of energy which are sufficient to “zap” any of the metallic particles on the chip detector, the electrical harnesses that connect the ECU and the chip detector/zapper need to fulfil specific design criteria for the pulses that are unique for the gas turbine engine harness (harnesses). For example, such harnesses increase the likelihood of electromagnetic interference and lightning threats in the energy generation system. Furthermore, the energy generation unit inside the electronic control unit needs to be shielded efficiently from other parts of the electronic control unit that may be operating at much lower voltage than that needed for generating the high energy pulses for the chip zapper. Therefore, generating the high energy pulses for the chip zapper inside the electronic control unit also presents potential challenges if high energy and low energy control units are arranged close to each other in the limited space of the ECU.
Thus, while presently known electronic control units and chip zappers are generally safe, reliable and robust, gas turbine engines with an electronic control unit including an energy generation unit for generating operational energy for the chip zapper can exhibit the above described drawbacks, in particular a large footprint inside the ECU, and increased weight due to the additional circuits in the electronic control unit and the potential challenges of electromagnetic interference and interaction as well as lightning threats.
Hence, there is a need for a gas turbine engine having an electronic control unit that uses relatively less components and/or occupies less space and/or weights than existing systems and which nevertheless guarantees that the chip zapping unit is supplied with sufficient operational energy for attracting the metal particles in the lubrication oil system. The present invention addresses one or more of these needs. In particular, the present invention aims at providing a system and a method for efficiently generating operational energy to be supplied to the chip sapping unit of a gas turbine engine.